package main

import (
	"fmt"
)

var (
	K        int
	OddDice  = []int{2, 3, 5, 7, 11, 13}
	CompDice = []int{4, 6, 8, 9, 10, 12}
)

func resolve() float64 {
	ret := 0.0
	for _, o := range OddDice {
		for _, c := range CompDice {
			if o*c != K {
				continue
			}
			ret += 1.0
		}
	}
	return ret / 36.0
}

func main() {
	fmt.Scanf("%d\n", &K)
	fmt.Println(resolve())
}